X-Git-Url: http://git.chise.org/gitweb/?a=blobdiff_plain;f=README;h=9fdf6d79baa5ea1ab9c28e271c4829f29bc2bc0e;hb=93ea9862c87f44d904ed46c383f6f395afcb082d;hp=2a780486ad6409bbfa8138707b4c76b5d4477677;hpb=80e5c7246f6205ed05c6f77deaa736d7e00eede1;p=elisp%2Fepg.git

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 * What's this?
 
-EasyPG is yet another GnuPG interface for Emacs.  It consists of two
-parts: transparent file encryption utility and easy-to-use elisp
-library to interact with GnuPG.
+EasyPG is yet another GnuPG interface for Emacs.  It consists of two parts:
 
-* Requirements
+- "The EasyPG Assistant" which provides basic GUI of GnuPG
+- "The EasyPG Library" which enables use of various features of GnuPG
+
+NOTE: EasyPG is neither a fork nor a re-implementation of Gnus/PGG.
 
-** GNU Emacs 21.4 or later
+* Requirements
 
-** XEmacs 21.4 or later
+** GNU Emacs 21.4 or XEmacs 21.4
 
-** GnuPG 1.4.3 or later
+** GnuPG 1.4.3
 
 * Quick start
 
-(0) Put (require 'epg-file) in your ~/.emacs.el
+** Installation
 
-(1) Restart emacs
+  $ ./configure
+  $ sudo make install
 
-(2) C-x C-f ~/test.gpg
+Add the following line to your ~/.emacs
 
-* Advantages over other competitors
+  (require 'epa-setup)
 
-There are many competitors of EasyPG such as Mailcrypt, PGG, gpg.el,
-etc.  EasyPG has some advantages over them.
+Then you can browse your keyring by `M-x epa-list-keys'.  In addition,
+you can do some cryptographic operations on dired.
 
-** EasyPG avoides potential security flaws of Emacs.
+  M-x dired
+  (mark some files)
+  : e (or M-x epg-dired-do-encrypt)
+  (select recipients and click [OK])
 
-*** `call-process-region' writes data in region to temporary files.
+* Security consideration
 
-`call-process-region' writes data in region to temporary files.  PGG
-and gpg.el use `call-process-region' to communicate with a gpg
-subprocess.  Your passphrases leak to the filesystem!
+There are security pitfalls around Emacs.
 
-*** There is no way to clear strings safely.
+** Passphrase may leak to a temporary file.
 
-If Emacs crashed and dumps core, passphrase strings in memory are also
+`call-process-region' writes data in region to a temporary file.
+The EasyPG Library does not use `call-process-region' to communicate with a gpg
+subprocess.
+
+** Passphrase may be stolen from a core file.
+
+If Emacs crashes and dumps core, Lisp strings in memory are also
 dumped within the core file.  `read-passwd' function clears passphrase
 strings by `(fillarray string 0)'.  However, Emacs performs compaction
 in gc_sweep phase.  If GC happens before `fillarray', passphrase
-strings may be moved elsewhere in memory.  It is recommended that as
-soon as you are done with passphrase you should clear it manually.
-However, PGG and gpg.el can keep passphrase strings in cache for a
-while and this behavior is their default!
-
-** Most GnuPG features are accessible from Emacs
+strings may be moved elsewhere in memory.  Therefore, passphrase
+caching in elisp is generally a bad idea.
 
-Other competitors provide only specific features of GnuPG.  As the
-name indicates, EasyPG is inspired by GPGME (GnuPG Made Easy), and the
-library interface is close to GPGME.  With EasyPG you can handle
-binary messages, sign/encrypt combined messages, etc.
+The EasyPG Library dares to disable passphrase caching.  Fortunately,
+there is more secure way to cache passphrases - use gpg-agent.  Elisp
+programs can set `epg-context-passphrase-callback' to cache user's
+passphrases, it is not recommended though.